Low-carb Nutrition – Greater Benefits or Losses

In a low-carbohydrate diet, the total consumption of carbohydrates is key, but how low is low and how high is still high to qualify a diet as low-carbohydrate? According to the nutritional standards of the Polish population, the lower limit of daily carbohydrate intake is 45% of the energy value (M. Jarosz et al. 2020). Therefore, the term 'low' can be used to describe the amount of carbohydrates below this value, however, specific ranges will have a significant impact on metabolism. In response to reduced access to carbohydrates and lower intake of insulin in the blood, the body should enter a state of increased fat-burning, which leads to ketosis. The production of ketone bodies is a response of the body to hunger. Ketones serve as an alternative source of energy for almost all cells, but not for all. Erythrocytes require glucose as the only source of energy, therefore, even if it is not provided through food, the body begins to produce it on its own (e.g., from certain amino acids, glycerol or lactic acid). In prolonged fasting, amino acids used in gluconeogenesis are derived from the breakdown of structural proteins, leading to a decrease in muscle mass, not only of skeletal muscles, but also of heart and smooth muscle mass, which form the structures of all organs. Below a certain threshold of carbohydrate intake, this metabolic change is particularly pronounced. The benefits of the ketogenic diet are interpreted with the assumption of 20-50 g of carbohydrates per day (F. Brouns 2018). If a larger amount is consumed in the liver, fewer ketone bodies are produced, therefore, it is assumed that the term 'low-carbohydrate' refers to a diet that includes up to 150 g of carbohydrates per day, which does not induce ketosis in the body, as in the case of the ketogenic diet (up to 50 g).